Low pressure control switch with bridging contacts

ABSTRACT

The present invention relates to a low pressure control switch for pump controls and includes a diaphragm actuated double contact switch for controlling both sides of the electric circuit. The diaphragm is spring returned and the spring tension can be adjustable to vary the low pressure at which the switch will break the circuit.

United States Patent 1 Burnett et al.

[ 51 May 22, 1973 [54] LOW PRESSURE CONTROL SWITCH WITH BRIDGING CONTACTS [76] Inventors: George R. Burnett; Jessie E, Burnett, both of N0. 2 Pye Court, El Dorado, Ark. 71730 [22] Filed: Dec. 6, 1971 [211 App]. No.: 204,863

[52] ILS. Cl ..200/83 J, 200/16 A, 200/83 S [51] Int. Cl. ..I-I0lh 35/34, H0111 1/20 [58] Field of Search ..200/83 J, 83 Z, 83 S,

[56] References Cited UNITED STATES PATENTS 9/1961 Giladett ..200/82 R X 8/1961 Putnam ..200/83 J X FOREIGN PATENTS OR APPLICATIONS 5/1957 Italy ..200/83J 7/1959 France ..200/83Z Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye Attorney-Alexander B. Blair [57] ABSTRACT The present invention relates to a low pressure control switch for pump controls and includes a diaphragm actuated double contact switch for controlling both sides of the electric circuit. The diaphragm is spring returned and the spring tension can be adjustable to vary the low pressure at which the switch will break the circuit.

2 Claims, 10 Drawing Figures PATENTED HA -Y2 2 I973 SHEET 1 BF 2 7114!! I!!! I IIV 1 IIIIIIIIIIIIIIII! IIIIII 1,111,,

JESS/E F. 502N577 ATTWMEY.

A A IIIIIIl-II I A A III] III, Iii/III! (1111!! III IIIIIIIIIIIIIII! I IIIII, 11,11! IIIIIIIIIIIIIIq LOW PRESSURE CONTROL SWITCH WITH BRIDGING CONTACTS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to circuit breakers for breaking the circuit to a pump motor under low pressure conditions.

SUMMARY OF THE INVENTION A diaphragm operated control switch for controlling both sides of the electric circuit with the pressure of actuation being adjustable.

The primary object of the invention is to provide a circuit controller which is actuated by low pressure in the pump circuit being controlled.

Other objects and advantages will become apparent in the following specification when considered in light of the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view through the low pressure controller of the invention;

FIG. 2 is a top plan view of the invention;

FIG. 3 is a fragmentary horizontal sectional view taken along the line 3-3 of FIG. 1 looking in the direction of the arrows;

FIG. 4 is a fragmentary horizontal section taken along the line 4--4 of FIG. 1 looking in the direction of the arrows;

FIG. 5 is a fragmentary horizontal sectional view taken along the line 5-5 of FIG. 1 looking in the direction of the arrows;

FIG. 6 is a fragmentary horizontal sectional view taken along the line 6-6 of FIG. 1 looking in the direction of the arrows;

FIG. 7 is a fragmentary horizontal sectional view taken along the line 7-7 of FIG. 1 looking in the direction of the arrows;

FIG. 8 is a horizontal sectional view taken along the line 8-8 of FIG. 1 looking in the direction of the arrows;

FIG. 9 is a horizontal sectional view taken along the line 9--9 of FIG. 1 looking in the direction of the arrows; and

FIG. 10 is a wiring diagram of the circuit used with the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail wherein like reference characters indicate like parts throughout the several figures the reference numeral 10 indicates generally a low pressure circuit controller constructed in accordance with the invention.

The circuit controller 10 is mounted in a generally rectangular box 11 having a hollow bell member 12 mounted therein on brackets 13. The bell member 12 has an externally threaded nipple l4 integrally secured to its lower end and extending out of the box 11. A reducing fitting 15 is provided with an annular flange 16 at its large end and an annular flange 17 at its small end. The bell 12 has an annular flange 18 formed on its upper edge which cooperates with the annular flange 16 to clamp a flexible diaphragm 19 therebetween. Bolts 20 extend to the flanges 16, 18 and the periphery of the diaphragm 19 to secure them together in a sealed manner. A tube 21 has a flange 22 on its lower end which is adapted to be secured to the flanges 17 by bolts 23. A flange 24 is secured to the tube 21 at its upper end and is adapted to be secured to the box 11 by means of bolts 25.

A plunger 26 is mounted for vertical reciprocation in the tube 21 and engages the diaphragm 19 at the lower end thereof. A cross bar 27 is secured to the plunger 26 by an upright bolt 28 extending downwardly therethrough. The cross bar 27 extends through slots 29 formed in opposite sides of the tube 21 and is adapted to reciprocate in the slots 29. A ring 30 is secured to the cross bar 27 outside of the tube 21 to retain the lower end of a coil spring 31 therein.

A plate 32 is mounted for reciprocation on the tube 21 in engagement with the upper end of the spring 31. Bolts 33 extend downwardly through the top of the box 11 and are adapted to bear against the plate 32 to adjust the tension in the spring 31. A contact plate 34 is secured to the cross bar 27 by means of a bolt 35. Springs 36 engage the top of the cross bar 27 and the bottom of the contact plate 34 to normally urge the contact plate 34 upwardly away from the cross bar 27. A contact plate 37 is secured to the cross bar 27 by means of a bolt 38. Coil springs 39 engage the contact plate 37 and the top of the cross bar 27 to normally urge the contact plate 37 away from the cross bar 27. A contact plate 40 is mounted on an insulating bracket 41 in a position overlying a portion of the contact plate 34. A contact plate 42 is secured to the insulating bracket 41 in a position to contact another portion of the contact plate 34. The contact plate 40 has a wire terminal 43 formed thereon. The contact plate 42 has a wire terminal 44 formed thereon. A contact plate 45 is mounted on an insulating bracket 46 to overlie a portion of the contact plate 37. A contact plate 47 is mounted on the insulating bracket 46 and is positioned to overlie another portion of the contact plate 37. A wire terminal 48 is formed on the contact plate 45 and a wire terminal 49 is formed on the contact plate 47.

A hand control bypass switch 50 is mounted in the box 11 and has a finger operated operated element 51 extending through the side wall of the box 1 1. A ground bolt 5 extends through the box 11 and is wired to the switch 50 when required.

In the use and operation of the invention the nipple 14 is connected into a pump circuit of the type operated by an electric motor 53. Since at this stage of operation there will be no pressure on the diaphragm 19 the spring 31 will force the cross bar 27 downwardly to disengage the contact plates 34, 37 from the contacts 40, 42 and 45, 47 respectively. With the contact bars 34, 37 out of engagement with the contacts 40, 42 and 45, 47 respectively no current can normally flow to the pump motor 53. In this situation the hand operated switch 52 is closed and the diaphragm actuated contact switch is bypassed energizing the motor 53. After the motor 53 is energized the pump brings the pump circuit up to pressure and this pressure is exerted on the diaphragm 19 to move the cross bar 27 upwardly so that the contact bars 34, 37 resiliently engage their respective contacts 40, 42, 45, 47. After this has occurred the switch 50 is opened so that the only circuit is then flowing through the contact bars 34, 37 and the contacts 40, 42, 45, 47.

Under these conditions should the pressure being pumped by the pump motor 53 fall below a predetermined preset minimum the diaphragm 19 will fall under pressure from the spring 31 and the bar 27 will be lowered moving the contact plates 34, 37 out of engagement with their respective contact plates. This will break the circuit to the motor 53 and require that the hand switch 50 be again used in order to establish the operation of the device.

It should be noted that many factors can cause the pressure to fall below the desired amount such as failure of the compressor, failure of the engine operating the compressor, opening of the line so that the material under pressure is liberated as well as other problems. Once the present invention has actuated itself to stop the flow of electricity to the pump motor no further operation of the pump motor can take place until the hand control switch is closed for a sufficiently long period of time to permit pressure to build in the system.

It should be understood that while there is shown two sets of contacts cooperating with two separate contact bars it may in some instances be desirable to break only one wire of the circuit in which case only one of the contact bars 34, 37 and one pair of the contacts 40, 42 45, 47 would be used.

Having thus described the preferred embodiments of the invention it should be understood that numerous structural modifications and adaptations may be resorted to without departing from the spirit of the invention.

We claim:

1. A low pressure circuit breaker comprising a chamber adapted to be connected to the pressure side of a pump, a diaphragm mounted in said chamber for actuation by pressure changes therein, a tube secured to said chamber and extending upwardly therefrom, a pair of opposed generally rectangular slots opening transversely through said tube, a plunger mounted for reciprocation in said tube and engaging said diaphragm for movement thereby, a cross bar secured to said plunger and extending outwardly of said tube through said slots therein, a pair of contacts positioned to overlie each end of said bar, a contact plate resiliently mounted on each end of said bar for respective engagement with the pair of contacts adjacent thereto, a coil spring surrounding said tube for engaging and biasing said bar in a direction to disengage said contact plates from said pairs of contacts, and a plate adjustably mounted on the upper end of said tube for engaging the upper end of said spring to adjust the tension of said spring against said bar.

2. A device as claimed in claim 1 including a hand actuated bypass switch electrically connected to said pairs of contacts for bypassing said contacts for start up operation of a pump. 

1. A low pressure circuit breaker comprising a chamber adapted to be connected to the pressure side of a pump, a diaphragm mounted in said chamber for actuation by pressure changes therein, a tube secured to said chamber and extending upwardly therefrom, a pair of opposed generally rectangular slots opening transversely through said tube, a plunger mounted for reciprocation in said tube and engaging said diaphragm for movement thereby, a cross bar secured to said plunger and extending outwardly of said tube through said slots therein, a pair of contacts positioned to overlie each end of said bar, a contact plate resiliently mounted on each end of said bar for respective engagement with the pair of contacts adjacent thereto, a coil spring surrounding said tube for engaging and biasing said bar in a direction to disengage said contact plates from said pairs of contacts, and a plate adjustably mounted on the upper end of said tube for engaging the upper end of said spring to adjust the tension of said spring against said bar.
 2. A device as claimed in claim 1 including a hand actuated bypass switch electrically connected to said pairs of contacts for bypassing said contacts for start up operation of a pump. 